An experimental method of wet compactness for plastic slurry was designed, and a new method of rapid drying shrinkage was set up for studying the change of drying shrinkage for hardened cement based materials in ovens of different temperature at different drying time. The results of this new rapid drying shrinkage method correspond to that under normal temperature, which can obviously shorten the drying cycle. The cement based materials having different compactness were prepared by using Portland cement as binder. And the effect of the compactness of cement based materials on its shrinkage cracking was investigated. The results show that with the decrease of the compactness of the cement based materials, the degree of plastic shrinkage can be restrained, and the drying shrinkage rate can be increased, whereas the effect on the degree of early drying shrinkage cracking of hardened cement based materials can be ignored.